Moisture Barrier Wall

ABSTRACT

A foundation system is disclosed that is used when building a structure on expansive soils. The foundation system includes a vertical wall that prevents moisture from migrating beyond the vertical wall into the zone of influence under the foundation. The prevention of the moisture migration into the zone of influence precludes damage to the foundation and structure caused by expansive soils.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/626,144, filed Nov. 25, 2009, which is incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates generally to structural foundations, andmore particularly to a vertical wall that prevents moisture frommigrating into the zone of influence of the soil under a foundation of aresidential or commercial building built in expansive soil areas.

BACKGROUND OF THE INVENTION

Several techniques have been used in the past to solve structuralproblems caused when buildings are built on expansive soils which shrinkand swell with moisture. Specifically, below-grade barriers can beinstalled after construction and after distress manifests itself in abuilding. These after the fact barriers are very expensive andintrusive. Moreover, these barriers are placed several feet beyond theexisting building slab or footing thereby necessitating an additionalbarrier to prevent moisture from migrating between the below-gradebarrier and the existing building slab or footing. Repairs after thefact are extremely costly depending on the amount of damage associatedwith the foundation movement due to the expansive soil below. Othersimilar barriers used to repair damage after the fact include cutoffwalls of concrete or synthetic membranes.

The use of after the fact remedial approaches to repair damages tostructures caused by expansive soils is more costly and time consumingthan installing a vertical wall to prevent moisture seepage at the timeof initial construction. With after the fact remedial procedures,landscaping is destroyed, mechanical units are relocated, patios anddriveways are torn up, and owners and occupants of the property aredisplaced for weeks at a time to allow time for the repairs.

In the prior art methods, post-tensioned concrete slabs have been usedto deal with expansive soils. This type of construction, however, isexpensive and requires extensive engineering and specializedconstruction techniques. Additionally, the floor plan designs arelimited due to the constraints inherent in post-tensioned slabs. Thecurrent invention eliminates these constraints, is simple to install andwill prevent the distress in buildings caused by foundation movementassociated with both expansive and collapsible soils. Therefore, it isdesirable to have a vertical wall that extends into the soil and isintegral with the building foundation in order to prevent moisture frommigrating into the zone of influence under the building foundation.

Various techniques have been disclosed in U.S. Pat. No. U.S. Pat. No.4,015,432 (H F Ball), U.S. Pat. No. 4,534,143 (Goines et al.), U.S. Pat.No. 5924251 Jalla), U.S. Pat. No. 4,508,472 (Handy), U.S. Pat. No.3,269,126 (Freeman), U.S. Pat. No. 1,746,918 (Webster), U.S. Pat. No.7,131,239 (Williams), U.S. Pat. No. 7,003,918 (Williams), U.S. PatentApplication Nos. 20080304919 (Coyle), 20030233798 (Berkey et al.),20030188496 (Williams), and International Publication No. WO 2005021874(Bashford) to overcome the problems with building on expansive soils.However, these disclosures suffer from one or more of the followingdisadvantages. First, none of these inventions include a vertical wallthat extends deep below the surface of the soil and is integral with thebuilding foundation. Second, none of these inventions are simple andinexpensive designs. Third, most of the inventions above are remedial innature rather than including a design that prevents foundation problemsat the time of initial construction.

SUMMARY OF THE INVENTION

A structural foundation for use in expansive or other soil comprises afoundational element. The foundational element is made of a verticalwall and a slab on a soil surface. The vertical wall is poured integralto the slab and the top of the vertical wall contacts the foundation.The bottom of the vertical wall extends a distance below the soilsurface and prevents moisture from migrating beyond the vertical wallunder the foundational element.

In an alternate embodiment, a foundation appurtenance for use inexpansive soils comprises a vertical wall and a foundation. Thefoundation further comprises a slab on a soil surface and a footingbelow the soil surface. The vertical wall is poured integral to thefooting and the top of the vertical wall contacts the footing. Thebottom of the vertical wall extends a distance below the soil surfaceand prevents moisture from migrating beyond the vertical wall under thefoundation.

The present invention is directed to a foundation used in expansivesoils to prevent water migration beyond a vertical wall into a zone ofinfluence under a building foundation.

It is a further object of the present invention to provide a foundationwith a vertical wall that is poured integral with the foundation.

It is a further object of the present invention to provide a foundationwith a vertical wall that is installed at the time of initialconstruction.

The novel features that are considered characteristic of the inventionare set forth with particularity in the appended claims. The inventionitself, however, both as to its structure and its operation togetherwith the additional object and advantages thereof will best beunderstood from the following description of the preferred embodiment ofthe invention when read in conjunction with the accompanying drawings.Unless specifically noted, it is intended that the words and phrases inthe specification and claims be given the ordinary and accustomedmeaning to those of ordinary skill in the applicable art or arts. If anyother meaning is intended, the specification will specifically statethat a special meaning is being applied to a word or phrase Likewise,the use of the words “function” or “means” in the Description ofPreferred Embodiments is not intended to indicate a desire to invoke thespecial provision of 35 U.S.C. §112, paragraph 6 to define theinvention. To the contrary, if the provisions of 35 U.S.C. §112,paragraph 6 are sought to be invoked to define the invention(s), theclaims will specifically state the phrases “means for” or “step for” anda function, without also reciting in such phrases any structure,material, or act in support of the function.

Moreover, even if the provisions of 35 U.S.C. §112, paragraph 6 areinvoked to define the inventions, it is intended that the inventions notbe limited only to the specific structure, material or acts that aredescribed in the preferred embodiments, but in addition, include any andall structures, materials or acts that perform the claimed function,along with any and all known or later developed equivalent structures,materials, or acts for performing the claimed function.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a preferred embodiment of the invention where the verticalwall is an appurtenance to the foundation and is located below a footingand a slab.

FIG. 1B shows a preferred embodiment of the invention where the verticalwall is an appurtenance to the foundation and is located below thefooting and slab wherein the footing and slab are poured as a monolithicpiece.

FIG. 2 shows a preferred embodiment of the invention where the verticalwall is part of the structural foundation and is located against andflush with the top of the slab.

FIG. 3 shows a preferred embodiment of the invention where the verticalwall is an appurtenance to the foundation and is located below the slab,stem, and footing.

FIG. 4 shows a preferred embodiment of the invention where the verticalwall is part of the structural foundation and is located below the slab.

FIG. 5 shows a prior art design of a remedial apparatus to repairfoundation damage due to migration of water into an expansive soil underthe foundation.

DESCRIPTION OF PREFERRED EMBODIMENTS

As described above, several techniques have been used in the past tosolve structural problems caused when buildings are built on expansivesoils 455 which shrink and swell with moisture. FIG. 5 shows one of theprior art methods. Specifically, FIG. 5 shows a foundation 300 thatincludes a slab 320, a stem 330, and a footing 340. Shown under thefooting 340 is the zone of influence 350 which is the area of soil wherewith the introduction of moisture the soil could expand and cause thefoundation 300 of a structure 400 built on the foundation 300 to move.The zone of influence 350 is defined based on the angle of repose. Morespecifically, the zone of influence is the area of soil that is locatedbelow the footing of the foundation and extends 45° on either side ofthe footing. When moisture enters the zone of influence 350, themoisture can cause the soil to move and in turn can cause the foundation300 to shift damaging the structure 400 built on the foundation 300. Toremedy the damage that has already occurred because of the migration ofmoisture into the zone of influence 350, the prior art shows at leastone cut off wall 600 that is placed a distance away from the foundation300. These remedial cut off walls 600 are intended to prevent furthermoisture from entering into the zone of influence 350 and causing moredamage to the foundation 300 and structure 400. As seen in FIG. 5,however, the remedial cut off walls 600 are placed away from thefoundation 300 allowing moisture to continue entering the zone ofinfluence 350. Moreover, because the cut off walls 600 are installedafter the structure has been built and the landscaping installed, plantsand mechanical equipment 100 must be moved causing more expense andtime.

In contrast, the preferred embodiments of the present invention shown inFIGS. 1A, 1B, 2, 3, and 4 show how a vertical wall 200 is pouredintegrally with the foundation 300 at the time of initial constructionso that moisture is prevented from entering the zone of influence 350and causing damage. There are several embodiments of the inventiondepending on the type of soil and the elevation at which the foundation300 and structure 400 will be constructed.

FIGS. 1A, 1B, and 3 show an embodiment of the current invention wherethe vertical wall 200 is an appurtenance to the foundation 300 ratherthan a structural element of the foundation 300. This embodiment ispreferred at elevations of 0-8,000 feet above sea level. Morespecifically, FIGS. 1A and 1B show the preferred embodiment forelevations 0-3,000 feet above sea level and FIG. 3 shows the preferredembodiment for elevations 3,000-8,000 feet above sea level.

In FIGS. 1A and 1B, a foundation system 300 is shown that includes aslab 320 and a footing 340. In FIG. 1A the slab 320 and footing 340 arepoured as two separate pieces where the slab 320 has a turndown edge 345that contacts the footing 340. In this embodiment, the topside 341 ofthe footing 340 contacts the underside 310 of the slab 320, and thefooting 340 and slab 320 work together as the structural foundationalsupport for a structure 400 built on the foundation 300. The structure400 may be conventional wood framing, masonry, and steel studs.Underneath the footing 340 is the vertical wall 200 where the top 210 ofthe vertical wall 200 contacts the underside 342 of the footing 340.

In the current invention, the vertical wall 200 acts to prevent moisturefrom migrating through the expansive soil 455 into the zone of influence350. As explained above, the zone of influence 350 is the area of soilthat when introduced with moisture could cause the foundation 300 tomove and damage the structure 400.

The depth of the slab 320 and footing 340 below the soil surface 450depends on the elevation above sea level of the area where the structure400 is being built. In the embodiment shown in FIG. 1A, the elevation ofthe area is 0-3,000 feet above sea level, and the depth of the slab 320and the footing 340 is preferably 12 inches below finished grade or thesoil surface 450. Because the vertical wall 200 contacts the underside342 of the footing 340 this 12 inch depth is also the depth at which thetop 210 of the vertical wall 200 is below the soil surface 450.

The vertical wall 200 extends a distance below the footing 340 such thatmoisture is prevented from migrating beyond the vertical wall 200 intothe zone of influence 350 under the foundation 300. In the preferredembodiment shown in FIG. 1A, the vertical wall 200 extends a minimum of3 feet 6 inches from the top 210 of the vertical wall 200 that contactsthe underside 342 of the footing 340 to the bottom 220 of the verticalwall 200. In other words, the bottom 220 of the vertical wall 200 is aminimum depth of 4 feet 6 inches below the soil surface 450. It ispreferred that the vertical wall 200 is 4 inches wide.

To create the foundation 300 shown in the preferred embodiment of FIG.1A, the area where the footing 340 will be poured is first excavated. Atrencher is then used to dig a 4 inch wide excavation in line with theouter edge 343 of the footing 340 a minimum of 3 feet 6 inches below theexcavation of the footing 340 as described above. This 3 foot 6 inchdepth can vary, however, depending on the exact make up of the soil. Thetrenched area is then cleaned and the 4 inch wide excavation is filledwith concrete to create the vertical wall 200. Preferably, theexcavation is filled with a ½ sack mix of concrete. Alternatively,however, the excavation could be filled with a grout mix, or any othermaterial with similar properties. In this embodiment, no additionalsteel reinforcement is needed because, as stated above, the verticalwall 200 is not part of the structural foundation but rather anappurtenance to the foundation 300. As such, the vertical wall 200 doesnot support the structure 400 so no reinforcement is needed. Once thevertical wall 200 is poured, the footing 340 is then poured with theproper concrete and steel reinforcements. In an alternate embodiment,the vertical wall 200 can be poured monolithically with the footing 340such that the vertical wall 200 and footing 340 are one piece. Pouringthe two pieces together saves time in construction. Additionally,depending upon the conditions, a waterproofing additive may be added tothe vertical wall 200 such that it is impervious to water.

Moreover, if it is determined that the soil 455 where the foundation 300and structure 400 are being built has a swell potential greater than 2%,a liner 500 is placed on the outside 230 of the vertical wall 200 thatfaces away from the slab 320. The liner 500 provides slippage of thevertical wall 200 in the soil 455 thereby eliminating friction thatcould cause the entire foundation 300 to move, thus causing damage tothe structure 400. It is preferred that the liner 500 is made of highdensity polyethylene with a thickness of 15-40 millimeters, but anymaterial with similar properties can be used.

In the embodiment shown in FIG. 1B, the slab 320 and footing 340 arepoured as one monolithic piece. Here, the footing 340 and slab 320 worktogether as the structural foundational support for a structure 400built on the foundation 300. The structure 400 may be conventional woodframing, masonry, and steel studs. Underneath the footing 340 is thevertical wall 200 where the top 210 of the vertical wall 200 contactsthe underside 342 of the footing 340 piece.

In this embodiment of the current invention, the vertical wall 200 actsto prevent moisture from migrating through the expansive soil 455 intothe zone of influence 350. As explained above, the zone of influence 350is the area of soil that when introduced with moisture could cause thefoundation 300 to move and damage the structure 400.

In this embodiment, the depth of the slab 320 and footing 340 below thesoil surface 450 depends on the elevation above sea level of the areawhere the structure 400 is being built. In the embodiment shown in FIG.1B, the elevation of the area is 0-3,000 feet above sea level, and thedepth of the footing 340 is 12 inches below finished grade or the soilsurface 450. Because the vertical wall 200 contacts the underside 342 ofthe footing 340, this 12 inch depth is also the depth at which the top210 of the vertical wall 200 is below the soil surface 450.

The vertical wall 200 extends a distance below the footing 340 such thatmoisture is prevented from migrating beyond the vertical wall 200 intothe zone of influence 350 under the foundation 300. In the preferredembodiment shown in FIG. 1B, the vertical wall 200 extends 3 feet 6inches from the top 210 of the vertical wall 200 that contacts theunderside 342 of the footing 340 to the bottom 220 of the vertical wall200. This means that the bottom 220 of the vertical wall 200 is a depthof 4 feet 6 inches below the soil surface 450. It is preferred that thevertical wall 200 is 4 inches wide.

To create the foundation 300 shown In the preferred embodiment of FIG.1B, the area where the footing 340 will be poured is first excavated. Atrencher is then used to dig a 4 inch wide excavation in line with theouter edge 343 of the footing 340 a minimum of 3 feet 6 inches below thefooting 340 as described above. This 3 foot 6 inch depth can vary,however, depending on the exact make up of the soil 455. The trenchedarea is then cleaned and the 4 inch wide excavation is filled withconcrete to create the vertical wall 200. Preferably, the excavation isfilled with a ½ sack mix of concrete. Alternatively, however, theexcavation could be filled with a grout mix. In this embodiment, noadditional steel reinforcement is needed because, as stated above, thevertical wall 200 is not part of the structural foundation but rather anappurtenance to the foundation 300. As such, the vertical wall 200 doesnot support the structure 400 so no reinforcement is needed. Once thevertical wall 200 is poured, the footing 340 and slab 320 are thenpoured with the proper concrete and steel reinforcements. In analternate embodiment, the vertical wall 200 can be poured monolithicallywith the footing 340 and slab 320 such that the vertical wall 200 andfooting 340 are one piece. Pouring the pieces together saves time inconstruction. Additionally, depending on the conditions, a waterproofingadditive may be added to the vertical wall 200 such that it isimpervious to water.

If it is determined that the soil 455 where the foundation 300 andstructure 400 are being built has a swell potential greater than 2%, aliner 500 is placed on the outside 230 of the vertical wall 200. Theliner 500 provides slippage of the vertical wall 200 in the soil 455thereby eliminating friction that could cause the entire foundation 300to move, thus causing damage to the structure 400. It is preferred thatthe liner 500 is made of high density polyethylene with a thickness of15-40 millimeters, but any material with similar properties can be used.

The embodiment in FIG. 3 shows a foundation 300 used for structures 400built at elevations between 3,000 feet and 8,000 feet. In thisembodiment, the foundation 300 includes a slab 320, a footing 340, and astem 330. The stem 330 is the structural piece between the slab 320 andthe footing 340. In this embodiment, the depth of the slab 320, stem330, and the footing 340 below finished grade, or soil level 450, isdependent on the elevation at which the structure 400 is beingconstructed. Specifically, at elevations of 3,000 to 5,000 feet, thedepth below soil level 450 is 18 inches; at elevations of 5,000 to 7,000feet, the depth below soil level 450 is 24 inches; and for elevations of7,000 to 8,000 feet, the depth below soil level 450 is 36 inches.Because the vertical wall 200 contacts the underside 342 of the footing340, these depths are also the depths at which the top 210 of thevertical wall 200 is below the soil surface 450.

The vertical wall 200 extends a distance below the footing 340 such thatmoisture is prevented from migrating beyond the vertical wall 200 intothe zone of influence 350 under the foundation 300. In the preferredembodiment shown in FIG. 3, the vertical wall 200 extends a minimum of 3feet 6 inches from the top 210 of the vertical wall 200 that contactsthe underside 342 of the footing 340 to the bottom 220 of the verticalwall 200. This means that the bottom 220 of the vertical wall 200 is adepth of 4 feet 6 inches below the soil surface 450. This total depthdepends, however, on the depth of the slab 320, stem 330, and footing340 below the soil surface 450 as explained above. Depending on theelevation at which the structure 400 is being built, the total depth ofthe vertical wall 200 will vary. It is preferred that the vertical wall200 is 4 inches wide.

To create the foundation 300 shown in FIG. 3, the area where the footing340 will be poured is first excavated. A trencher is then used to dig a4 inch wide excavation in line with the outer edge 343 of the footing340 a minimum of 3 feet 6 inches below the footing 340 as describedabove. This 3 foot 6 inch depth can vary, however, depending on theexact make up of the soil 455. The trenched area is then cleaned and the4 inch wide excavation is filled with concrete to create the verticalwall 200. Preferably, the excavation is filled with a ½ sack mix ofconcrete. Alternatively, however, the excavation could be filled with agrout mix. In this embodiment, no additional steel reinforcement isneeded because, as stated above, the vertical wall 200 is not part ofthe structural foundation 300, but rather an appurtenance to thefoundation 300. As such, the vertical wall 200 does not support thestructure 400 so no reinforcement is needed. Once the vertical wall 200is poured, the footing 340, stem 330, and slab 320 are then poured withthe proper steel reinforcements and concrete. In an alternateembodiment, the vertical wall 200 can be poured monolithically with thefooting 340 such that the footing 340 and vertical wall 200 are onepiece. Pouring the pieces together saves time in construction.Additionally, depending on the conditions, a waterproofing additive maybe added to the vertical wall 200 making it impervious to water.

If it is determined that the soil 455 where the foundation 300 andstructure 400 are being built has a swell potential greater than 2%, aliner 500 is placed on the outside 230 of the vertical wall 200. Theliner 500 provides slippage of the vertical wall 200 in the soil 455thereby eliminating friction that could cause the entire foundation 300to move, thus causing damage to the structure 400. It is preferred thatthe liner 500 is made of high density polyethylene with a thickness of15-40 millimeters, but any material with similar properties can be used.

FIGS. 2 and 4 show an embodiment of the current invention where thevertical wall 200 is a structural element of the foundation 300. Morespecifically, FIG. 2 shows a preferred embodiment where the verticalwall 200 comes out of the soil surface 450 and is poured up against andflush with the top of the slab 320. The preferred embodiment shown inFIG. 4 depicts the vertical wall 200 on the underside 325 of the slab320.

The embodiment in FIG. 2 shows a foundation 300 that includes a slab 320and a vertical wall 200. In this embodiment, the vertical wall 200 actsas the footing 340 while at the same time preventing moisture frommigrating beyond the vertical wall 200 into the zone of influence 350.The vertical wall 200 includes a top portion 240 and a bottom portion260. The top portion 240 of the vertical wall 200 extends 12 inches inheight and is formed to accommodate the final vertical wall 200thickness. This thickness of the vertical wall 200 is preferably 8inches, but can be thicker by widening the vertical wall 200 dependingon the conditions. The bottom portion 260 of the vertical wall 200starts 12 inches below the top 210 of the vertical wall 200 and extendsa minimum depth of 4 feet 6 inches to the bottom 220 of the verticalwall 200 in order to prevent moisture from migrating beyond the verticalwall 200 into the zone of influence 350.

To create the foundation 300 shown in the preferred embodiment of FIG.2, a trencher is used to dig an 8 inch wide excavation 4 feet 6 inchesbelow the soil surface 450 or as desirable or required by code. Thetrenched area is cleaned and the excavation is filled with concrete tocreate the vertical wall 200. It is preferred that the concrete isnormal 2500 psi concrete. Steel reinforcements are included in thevertical wall 200 along with vertical bars. The reinforcements arerequired because the vertical wall 200 is part of the structuralfoundation of the structure 400. The slab 320 is then poured up againstand flush with the top 210 of the vertical wall 200 as shown in FIG. 2.In an alternate embodiment, the vertical wall 200 can be pouredmonolithically with the slab 320 such that the vertical wall 200 andslab 320 are one piece. Additionally, depending on the conditions, awaterproofing additive may be added to the vertical wall 200 such thatit is impervious to water.

If it is determined that the soil 455 where the foundation 300 andstructure 400 are being built has a swell potential greater than 2%, aliner 500 is placed on the outside 230 of the vertical wall 200. Theliner 500 provides slippage of the vertical wall 200 in the soil 455thereby eliminating friction that could cause the entire foundation 300to move, thus causing damage to the structure 400. It is preferred thatthe liner 500 is made of high density polyethylene with a thickness of15-40 millimeters, but any material with similar properties can be used.

The embodiment in FIG. 4 shows a foundation 300 that includes a turndownslab 320 and a vertical wall 200. In this embodiment, the vertical wall200 acts as the footing 340 while at the same time preventing moisturefrom migrating beyond the vertical wall 200 into the zone of influence350 under the foundation 300. The vertical wall 200 includes a top 210and a bottom 220. The top 210 of the vertical wall 200 contacts theunderside 325 of the turn down slab 320 10 inches below the topside 321of the slab 320. Therefore, it is preferred that the top 210 of thevertical wall 200 starts 10 inches below the topside 321 of the slab 320and extends a depth of 4 feet 6 inches to the bottom 220 of the verticalwall 200 in order to prevent moisture from migrating beyond the verticalwall 200 through the soil 455 into the zone of influence 350 under thefoundation 300. In this embodiment, it is preferred that the verticalwall is 8 inches wide.

To create the foundation in the preferred embodiment shown in FIG. 4, atrencher is used to dig an 8 inch wide excavation 4 feet 6 inches belowthe soil surface 450 or as desirable or required by code. The trenchedarea is cleaned and the excavation is filled with concrete to create thevertical wall 200. It is preferred that the concrete is normal 2500 psiconcrete. Steel reinforcements are included in the vertical wall 200along with vertical bars. The reinforcements are required because thevertical wall 200 is part of the structural foundation of the structure400. The outer edge 323 of the slab 320 is formed to accommodate theslab 320 thickness and the small portion of the stem wall 331 requiredto bring the slab 320 to finished floor elevation. Additionally,depending on the conditions, a waterproofing additive may be added tothe vertical wall 200 such that it is impervious to water.

If it is determined that the soil 455 where the foundation 300 andstructure 400 are being built has a swell potential greater than 2%, aliner 500 is placed on the outside 230 of the vertical wall 200. Theliner 500 provides slippage of the vertical wall 200 in the soil 455thereby eliminating friction that could cause the entire foundation 300to move, thus causing damage to the structure 400. It is preferred thatthe liner 500 is made of high density polyethylene with a thickness of15-40 millimeters, but any material with similar properties can be used.

The preferred embodiment of the invention is described in theDescription of Preferred Embodiments. While these descriptions directlydescribe the one embodiment, it is understood that those skilled in theart may conceive modifications and/or variations to the specificembodiments shown and described herein. Any such modifications orvariations that fall within the purview of this description are intendedto be included therein as well. Unless specifically noted, it is theintention of the inventor that the words and phrases in thespecification and claims be given the ordinary and accustomed meaningsto those of ordinary skill in the applicable art(s). The foregoingdescription of a preferred embodiment and best mode of the inventionknown to the applicant at the time of filing the application has beenpresented and is intended for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed, and many modifications andvariations are possible in the light of the above teachings. Theembodiment was chosen and described in order to best explain theprinciples of the invention and its practical application and to enableothers skilled in the art to best utilize the invention in variousembodiments and with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. A device for preventing moisture from migratinginto a structure's zone of influence in expansive soil, the devicecomprising in combination: a structure, and a vertical wall locatedbelow the structure and located at least partially underground, thevertical wall placed contemporaneously with or prior to construction ofthe structure; the vertical wall configured to form a vertical skirtaround the expansive soil underneath the structure; the vertical wallcomprising at least some structural connection to a perimeter of thestructure; and the vertical wall configured underneath the perimeter ofthe structure so that an outside face of the vertical wall and anoutside face of the structure form a single vertical plane.
 2. Thedevice of claim 1, further comprising a liner on the outside face of thevertical wall.
 3. The device of claim 1, the vertical skirt extending atleast 18 inches below the soil surface.
 4. The device of claim 1, thevertical wall comprising concrete.
 5. The device of claim 1, wherein thestructure is a concrete slab.
 6. The device of claim 1, the verticalwall comprising grout or a slurry mix.